Comminution process to produce wood particles of uniform size and shape with disrupted grain structure from veneer

Abstract

Comminution process of wood veneer to produce wood particles, by feeding wood veneer in a direction of travel substantially normal to grain through a counter rotating pair of intermeshing arrays of cutting discs arrayed axially perpendicular to the direction of wood veneer travel, wherein the cutting discs have a uniform thickness (Td), to produce wood particles characterized by a length dimension (L) substantially equal to the Td and aligned substantially parallel to grain, a width dimension (W) normal to L and aligned cross grain, and a height dimension (H) aligned normal to W and L, wherein the W×H dimensions define a pair of substantially parallel end surfaces with end checking between crosscut fibers.

We claim: 
     
       1. A process of comminution of a wood veneer to produce wood particles, wherein the wood veneer is characterized by a grain direction and a maximum thickness (Tv), wherein the comminution process consists essentially of feeding the wood veneer in a direction of travel substantially normal to the grain direction through a counter rotating pair of intermeshing arrays of cutting discs arrayed axially perpendicular to the direction of wood veneer material travel, wherein the cutting discs have a uniform thickness (Td), to produce wood particles characterized by a length dimension (L) substantially equal to the Td and aligned substantially parallel to the grain direction, a width dimension (W) normal to L and aligned cross grain, and a maximum height dimension (H) substantially equal to the Tv and aligned normal to W and L, wherein the L×H dimensions define a pair of substantially parallel side surfaces with substantially intact longitudinally arrayed fibers, the W×H dimensions define a pair of substantially parallel end surfaces with crosscut fibers and a disrupted grain structure characterized by end checking between fibers, and the L×W dimensions define a pair of substantially parallel top and bottom surfaces. 
     
     
       2. The comminution process of  claim 1 , wherein the direction of wood veneer travel is aligned within about 30° parallel to the grain direction. 
     
     
       3. The comminution process of  claim 2 , wherein the direction of wood veneer travel is aligned within about 10° parallel to the grain direction. 
     
     
       4. The comminution process of  claim 1 , wherein Td÷Tv=4 or less. 
     
     
       5. The comminution process of  claim 4 , wherein Td÷Tv=2 or less. 
     
     
       6. The comminution process of  claim 1 , wherein the Td is between 1/32 inch and ¾ inch. 
     
     
       7. The comminution process of  claim 6 , wherein the Td and the Tv are such that at least 80% of the produced wood particles pass through a ¼ inch screen having a 6.3 mm nominal sieve opening but are retained by a No. 10 screen having a 2 mm nominal sieve opening. 
     
     
       8. The comminution process of  claim 1 , wherein the Td and the Tv are such that at least 90% of the produced wood particles pass through either: an ¼ inch screen having a 6.3 mm nominal sieve opening but are retained by a ⅛-inch screen having a 3.18 mm nominal sieve opening; a No. 4 screen having a 4.75 mm nominal sieve opening screen but are retained by a No. 8 screen having a 3.18 mm nominal sieve opening; a ⅛-inch screen having a 3.18 mm nominal sieve opening but are retained by a No. 16 screen having a 1.18 mm nominal sieve opening; a No. 10 screen having a 2.0 mm nominal sieve opening but are retained by a No. 35 screen having a 0.5 mm nominal sieve opening; a No. 10 screen having a 2.0 mm nominal sieve opening but are retained by a No. 20 screen having a 0.85 mm nominal sieve opening; or, a No. 20 screen having a 0.85 mm nominal sieve opening but are retained by a No. 35 screen having a 0.5 mm nominal sieve opening. 
     
     
       9. The comminution process of  claim 1 , wherein the wood veneer is selected from among the group consisting of peeled softwood and hardwood veneers, sawed softwood and hardwood veneers, and sliced softwood and hardwood veneers. 
     
     
       10. The comminution process of  claim 1 , wherein the wood veneer is comminuted in a green, seasoned, or rehydrated condition. 
     
     
       11. The comminution process of  claim 10 , wherein the wood veneer is comminuted at a retained field moisture content greater than about 30% wwb.